The present invention relates to a keyboard comprising entry keys to perform exposure compensation and color correction for use in a photographic printing apparatus.
In a known photographic printing apparatus, an optimum of exposure for a desired picture frame of a color negative film is determined by measuring a total transmitted portion of irradiation of light falling on the negative frame. It is however difficult to make prints perfectly with 100% exposure because the frames vary from each other in the conditions of shooting and the type of object.
For compensation, each frame of the color negative film or its simulated image is viewed and examined by the operator of the photographic printing apparatus. More specifically the operator enters corrected values of exposure to a computer using entry keys of a keyboard to produce a print with an optimum result.
Such a keyboard associated with a conventional photographic printing apparatus comprises a set of entry keys 20 to 29 arranged linearly in a horizontal row on a board base A2 as shown in FIG. 2. Another keyboard shown in FIG. 3 has a set of entry keys 30 to 39 arranged in a matrix on a board base A3, similar to the arrangement of common ten keys.
The former arrangement is capable of accommodating a multiplicity of keys in a given space for the purpose of space saving. The disadvantage of such arrangement is that the lateral movement of a hand H of the operator in selecting desired entry keys is extensive to left and right as defined by the arrow in FIG. 2, thus causing the operator to stretch his or her arm A.
The latter key arrangement is not designed to ease the continuous action of operating the keys. In fact, the operator needs to move his or her arm A in zigzag or crosswise actions as show in FIG. 3.
As understood, the conventional keyboards for a photographic printing apparatus are rather low in controllability. Also, their home positions are not obvious, thus making it difficult for beginner operators to learn a blind-touch typing technique.
It is an object of the present invention to provide a keyboard for use in a photographic printing apparatus comprising a specific arrangement of entry keys which is operable without the need of an operator moving his or her arm and which offers ease of continuous typing.